This is a proposal to study the perception of relations in time and space of events which originate in different sense modalities. The basic problem to which this study is addressed concerns the hypothesis that events which occur in different sense modalities are independently ordered in space and time prior to the perception of their relations. The alternative hypothesis is that sensory events are given spatial and temporal orders in common centers. For convenience these two propositions are called the multiple channels hypothesis and the single channel hypothesis respectively. A supplementary proposition is that perceptual learning and development would proceed differently in a multiple channels system than it would in a single channel system. A number of experiments are proposed to test these hypotheses. These experiments entail the matching of lights and sounds so that they appear to occur simultaneously, tests of the independence of the auditory and visual position sensing channels, the presence or absence of intersensory beats, the effect of delay of visual feedback on visual capture of tactual perception and of delay of auditory information on judgments of simultaneity. The perceptual adaptation paradigm will be used in some studies. Attempts will be made to obtain objective indices of intersensory processes by means of evoked potentials. These methods, as well as psychophysical methods, will be used and developed with adults as subjects and then applied to normal children and with children having perceptual and motor disorders. This will permit us to test the proposition that at least some learning disabilities reflect disturbance of intersensory function and to obtain basic data on the development of such functions.